I think this is key. There are studies that point to handwriting notes helping with the learning process, even if you don't end up using them later. I always found this to be true for myself as well — whether I'm in a lecture or doing some study on my own. I don't often go back to them unless I need to refresh on a single point. If I write them, I don't need them as much. If I don't write them, I'm usually having to study and read more and return to the references.

https://www.scientificamerican.com/article/a-learning-secret...

It really depends on how the notes were taken. Jotting down thoughts when you study on your own is helpful. But it's extremely common for your brain to just copy words from the board / screen to the notebook without any cognitive involvement.

I think this was a big part in why pen-and-paper outperformed typing for me.

I'm slow at handwriting; to keep up with a lecture I basically have to use shorthand and restrict myself to the most useful observations. But typing, I can just be a pipe moving every word from powerpoint to a text file. That distracts me from the content of the lecture and doesn't do anything for retention.